Oil and natural gas are crucial commodities in the world's supply of energy resources. As such, the excavation of these commodities from beneath the surface of the earth is an important activity in the energy industry. Several companies dedicate immense time and effort to the efficient extraction of oil and natural gas from the subsurface.
To obtain hydrocarbons from beneath the earth's surface, energy producers use complex operations and a variety of technologies to obtain the hydrocarbons from different sources. Hydrocarbons may be found, for example, in oil rich sands and deposits located in geological formations beneath the earth. A recently profitable technique for extracting these resources is known by those in the art as “hydraulic fracturing” and is also known in the industry as “fraccing.” This method generally includes drilling a subsurface well bore, providing perforations in the well bore, and injecting a fracture fluid into the perforated hole. The fracture fluid is pumped into the well bore at elevated pressure, thereby causing fissures or fractures to open beneath the surface. Resources such as oil and natural gas flow from the fractures into the well bore, where they can be relayed to the surface. An example method of hydraulic fracturing is disclosed in U.S. Pat. No. 3,654,992 to Harnsberger et al.
In many situations, the fracture formation process can be improved by incorporating a material known as “proppant.” Proppant refers to any of a variety of materials that can be mixed with the fracturing fluid. Proppant is so named because it is made up of particles which “prop open” a fracture formed by hydraulic fracturing fluid for as much time as is needed for the new fracture to deplete the reservoir. Suitable proppant materials can include sands, glass, mortar, or other particulate solids that can easily remain inside the opened fracture. Proppant may be helpful because it tends to maintain stability in the opened fracture, thereby allowing extraction of hydrocarbons or other fluids.
In practical applications, proppant can work more effectively when it is concentrated at the spatial interface between the well bore and the newly created fracture. If proppant is highly concentrated in this area, the fracture may cover a larger spatial volume and remain stable more easily. This interface area, where proppant tends to be most effective, is sometimes called the “critical zone.”